Copy Constructor DIP and implementation

[RazvanN]

Hi all,

I just pushed another version of the DIP in which the major 
modifications among otthers are removing implicit and use copy 
constructor calls in all situations where a copy is made. For 
more details, please visit [1] and if you have the time, please 
offer some feedback,

Thank you,
RazvanN

[1] https://github.com/dlang/DIPs/pull/129/